Transformer



G. CAMILLI TRANSFORIIER Aug. 1, 1939-.

Filed u'arch 16, 1958 Pag. 5.

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Patented Aug. 1, 1939 UNITED STATES PATENT OFFICE TRANSFORMER Guglielmo Camilll, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application March 16, 1938, Serial No. 196,239 s claims. (ci. 17o-361) My invention relates to transformers and its face of the transformer. The transformer may general object is to provide an improved trans- -be dipped in the paraflin several times if necesformer construction and an improved method of sary to provide a paraffin coating or film of deproducing such construction in which the transsired thickness, as indicated in the sectional view former is embedded in concrete. A concreteof Fig. 3. Some of the paraffin coating I3 on 5 encased transformer constructed in accordance the magnetic core I0 may be scraped olf if dewith the invention is fireproof and weatherproof. sired as it may not all be necessary. The thin It may be produced very economically and it has lm of paraffin on the magnetic core IIJ will progood load capacity because the heat conductivity tect it from the effects of moisture from the 'conof concrete is good. crete to be applied later which might cause 10 There is a difference in the thermal expansion rusting and a consequent increase in core losses of the concrete and of the transformer parts during operation. After the transformer has and this tends to cause trouble if the concrete beenv provided with the coating or film I3 of is cast directly onto the transformer. Thus, the parailn, the transformer is placed in a casing ,difference in thermal expansion may cause the I4 and the Space around the transfOlIner C0111- concrete and the transformer to separate slightly pletely filled with a body of concrete I5, as shown and leave voids in which corona may appear or in Fig. 4. BefOre the COnCrete I5 ls poured it may cause such pressure as to crack the conaround the transformer, a plug or rod I6 is crete. An object of the invention is to provide placed With its lOWer end' in Contact With the n an improved method and construction which Derailn layer I3 and' With its upper end eX- 20 avoids any danger of these troubles. tending at least to the level to which the con- The invention will be better understood from Crete is t0 be DOlued. After the COnCiete has the following description vtaken in connection hardened, it shOuld be thOl'Oughly dried by heatwith the accompanying drawing in which Fig. 1 ing it in a partial vacuum. The plug I6 is now u shows a transformer partly in sectionlbefore it removed and the transformer with its concrete has been treated to prepare it for its concrete Casing turned upside dOWn. es ShOWnin Fig 5. casing; Fig. 2 shows the transformer after treat- The transformer is heated Suflieiently t0 melt ment; Fig. 3 is a sectional view of a portion of the paraffin layer I3 S0 that it Will drain Out the transformer shownin Fig. 2; Fig. 4 is a secthl'Ough the Opening Il left by the leInOVal 0f the tional View of the transformer with its concrete -Plug I6. This Will leaVe e SP2-Ce I3 between the 30 casing; Fig. 5 is a View, partly in Section, of the concrete casing I5 and the transformer windings transformer showing a step in the process of' II and I2 The transformer is 110W turned right -producing it; Fig. 6 is a sectional View of a por- Side up, as ShOWn in Fig- 6, and the SDaCe I3 tion of the completed transformer; and Fig. 7 is lled an insulating liquid I9 preferably t0. an explanatory detail of a modified form of casing a level somewhere in the Opening Il. The outer for the transformer. end of the opening I'Imay be closed by a stopper Like reference characters indicate similar parts 20 leaving] an expansion Chamber 0I Space bein the different figures of the drawing. tween the stepper and the liquid as shown in The invention is particularly applicable in con- 'Elg 6 t/o permit thermal expansion and contracnection with transformers of rather small size ti'On Of the liqllid- The insulating liquid. I9 PIO- 40 .S'o that. the Weight 0f the Concrete casing may Vides BllClEIlt insulation around the windings Il not be objectionable, such a transformer being and I2 and prevents the fOrmtlOn 0f any voids indicated in Fig. l and including a magnetic core between the windings and the concrete casing lo provided with windings H and l2. The core l5 by unequal thermal expansion and contracand windings of the transformer should first be tlOn 0f the Wlndings'and the COnCrete Casing- It 45 thoroughly dried by any suitable process, such also permits unequal thermal expansion of the as by heating the transformer in a partial vacu- Concrete and transformer without Causing presum. The transformer is next cooled and pro- Sure Which might Crack the Concrete- The videdwith a coating or lm I3 of parafn or f necessary thickness 0f the liquid lm Will Vary other suitable wax which is solid when cold with the size of the transformer but may be of but which may be easily melted by heating' it. the order of one eighth inch or perhaps less for The paraffin coating or nlm I 3 may be quickly small transformers so that the Vconcrete casing applied by dipping the transformer in a tank of will conform closely and intimately to the surmolten parainand quickly removing it to allow face of the transformer, the casing being spaced the paraffin adhering toit to harden on the sur' from the transformer only by the liquid film. 55

'Ihe casing I4 may be a permanent metal casing if desired or it may be merely a form to hold the concrete casing `I51while Vthe `concrete, is being cast around the transformer, in which case it may be removed after it has served this purpose. If the casing Il is removed from the concrete, however, the insulating liquid I9 will tend to penetrate outwardly through the pores of the concrete and rgradually escape. To prevent this loss of the insulating liquid I9, the outer surface of the 'concrete casing I5 may be impregnated with a layer 2| of some liquid, such as linseed oil, which may be hardened by heat to provide a layer imprevious to the insulating liquid I9. The surface may then be given a coating 22 of 'paint to improve its appearance.

The concrete casing I5 has good heat conductivity so that the heat generated by the losses in the transformer is rapidly dissipated and the load capacity of the.transformer is consequently also good. I

The invention has been explained by describing a transformer structure and a method for producing it inA accordance with the invention but it will be apparent that changes may be made without departing from the spirit of the invention and the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination of a transformer, a one` piece concrete casing surrounding said transformerand intimately conforming to its surface, and a thin lm of insulating liquid surrounding the transformer between the transformer and casing, said casing being spaced from the transformer only by the liquid film.

2. The combination of a transformer, a onepiece vconcrete casing surrounding said trans-7 former and intimately conforming to its surface, athin film of insulating liquid surrounding the transformer between the transformer and casing, and a liquid impervious layer impregnating the outer surface of the concrete casing, said casing being spaced from the transformer only by the liquid film.

3. A method of producing a concrete-encased transformer, said method including the steps of coating a transformer with a hardened film, casting a concrete casing around the film-.coated transformer, melting and draining out said film, and filling the spacebetween the transformer and the concrete casing with an insulating liquid.

4. A method of producing a concrete-encased transformer, said method including the steps of coating a transformer with a hardened film, casting a concrete casing around the film-coated transformer, melting and draining out said film, filling the space between the transformer and the concrete casing with an insulating liquid, and irnpregnating the outer surface of the concrete with a liquid impervious layer.

5. A method of producing a concrete-encased transformer, said method including the steps of drying a transformer, coating the dried transformer with a hardened lm of wax, casting a concrete casing around the film-coated transformer, melting and draining out said'lm, vand filling the space between the transformer and the concrete casing with an insulating liquid.

6. The combination of a transformer, a onepiece concrete casing surrounding said trans-l former and intimately conforming to its surface, a thin nlm of insulating liquid surrounding the transformer between the transformer and casing,

- said casing being spaced from the transformer only by the liquid nlm, and an expansion chamber communicating with said liquid film to permit thermal expansion and contraction of the liquid.

GUGLIELMO CAMELLI. 

